Method for recording and transmitting a multi-channel ECG and an arrangement as a portable recorder for carrying out this procedure

ABSTRACT

Method for recording and transmitting a multi-channel ECG and arrangement as a portable recorder for carrying out the procedure.  
     The invention concerns a method for recording and transmitting a multi-channel ECG and an arrangement as a portable recorder for carrying out the procedure as part of a telemedical system (ECG-recorder—mobile telephone—evaluation center).  
     The purpose of the invention is to enable automatic transmission of the recorded ECG in any length using a conventional, mobile radio controlled telephone.  
     The invention fulfils this purpose in that following a multi-channel amplification ( 2 ) A/D conversion ( 3 ) and processing by a pacemaker controller ( 10 ) takes place and both are passed on to a microcontroller ( 4 ) for further processing and storage with subsequent transmittance via a serial interface ( 7 ) to an aforementioned mobile telephone ( 8 ) or a PC ( 9 ). In addition a removable flash card ( 6 ) is also allowed for, by means of which, for example, data can be read in at another location.

[0001] The invention belongs to the field of medical technology andrelates the reading, recording and transmittance of bioelectricalsignals of the body or parts of the same for diagnostic purposes, in sofar as it is a method for recording and transmitting a multi-channel ECGand an arrangement as a portable recorder for carrying out thisprocedure. This procedure and this arrangement is part of a telemedicalsystem (ECG-recorder—mobile telephone—evaluation center) which forms thebasis for a mobile ECG monitoring system for high-risk patients.

[0002] Equipment for mobile patient monitoring is mainly known in theform of two differing types of devices, and the associated but differingmethods. The first group of devices includes mobile telephones.Representatives of these are, for example, the technical solutionsdescribed in patent specifications EP 0 679 041 A2 and DE PS 197 07 681C1. The technical solution described in patent specification EP 0 679041 A2 is solely suitable for determining the location of the patientusing his positional data. In the case of the technical solutiondescribed in the aforementioned patent specification DE PS, the selectedmedical data is measured by means of special contacts on the mobiletelephone which are fitted to the body of the patient or attached bymeans of wiring and transmitted over the radio communications network,following which immediate aid measures can be taken. Going beyond thesimple determination of the position of the patient as described in theaforementioned EP patent specification, here the current data istransmitted immediately, in contrast to the aforementioned EP solution,in order to identify the patient and/or to record the ECG signals. Adisclosure of which, that such an aforementioned mobile telephoneindependently monitors the patient and in a medically significant eventautomatically transmits the recorded data over the radio communicationsnetwork, cannot be proven, in particular, but also just because of thisreason, cannot be assumed, as an emergency call button on the devicewhich is to be operated by the patient is specified, which the patienthimself can or must operate in threatening situations. It must be notedthat the disadvantage of these aforementioned technical solutions isthat it is not possible to store and record large amounts of relevantdata in the case of monitoring measures conducted uninterruptedly over along period, for several days, weeks or months. An operating facilityfor transmitting stored and recorded data to a “central” computer forthe purpose of evaluating the time course of the relevant data is alsonot disclosed. Therefore, in the case of the aforementioned solutions,only the data relating to the normal momentary situation or a specialmomentary event is transmitted, and not the case history leading up tothe event and its subsequent evaluation. Furthermore, these radiotelephones differ considerably from conventional devices designed fortelephoning, as they are special devices employing special applicationsystems and are for the main part scarcely designed or suitable forconventional telephoning purposes.

[0003] The second group of devices includes the recorders.

[0004] Several types of recorders designed to be worn on the body havebecome known.

[0005] So-called long-term ECG recorders generally record the ECG of thepatient continuously, usually over a period of 24 hours, by means of anelectronic memory. These recorders with integrated data carriers arethen given to the doctor. The data is read out or removed and evaluatedat a later time.

[0006] With so-called event recorders a brief ECG period, usuallymeasured in seconds, is recorded and transmitted in the event of acritical heart event or at predefined intervals. This data istransmitted by telephone using a fixed-network telephone in acomplicated procedure. The stored ECG is modulated into an audiofrequency enabling it to be transmitted by telephone to an evaluationcenter.

[0007] In the case of so-called event recorders with looping function,an ECG is continuously stored by means of electrodes attached to thebody and then repeatedly overwritten after a period of seconds orminutes. If an event occurs the case history immediately prior to theevent is herewith stored. The ECG is then transmitted to the evaluationcenter as in the case of the previous event recorders.

[0008] Recently recorders that can be implanted have become known. Theinternal ECG memory allows data to be stored for up to approximately anhour. The ECG can be read out externally.

[0009] The particular disadvantageous technical effects of theseaforementioned technical solutions with regard to their arrangement andmethod characteristics are described below.

[0010] Long-term EGG recorders only allow the ECG to be analyzed, andtherefore pulse irregularities to be detected, after the data has beenrecorded. The patient is only monitored for 24 or 48 hours, and controlresults can only be recognized after a further, considerable delay.Consequently only a diagnosis, also termed a “follow-up diagnosis”, ispossible which—in the case of rare events—offers an extremely limiteddegree of accuracy and which makes the development, for example in thecase of medicinal therapy, practically impossible.

[0011] Event recorders are designed to circumvent the disadvantage ofthe “follow-up diagnosis” to as great an extent as possible. ECG eventsor phases are recorded. However, these are then transmitted to anevaluation center using a complicated and time-consuming procedure,which inherently leads to a reduction in quality and requires afixed-network telephone with audio frequency modulation. The entireprocess is extremely difficult to manage, which severely restricts itsuse in the age group most at risk, if not making it impossiblealtogether. Furthermore, a real transmission of data is scarcelypossible in an emergency situation. The mobility of the patient isrestricted by the required fixed-network telephone. The help of a secondperson is usually required due to the complicated procedure involved,which is very likely to lead to incorrect use under stressfulcircumstances. Another factor in the case of the first group ofrecorders is that a brief event is never recorded as the patient himselfmust first recognize that an event has occurred, and this is thenunavoidably only recorded once it has happened. The diagnostic value istherefore extremely limited.

[0012] Although implanted recorders require no effort to be operated,they do need to be implanted and must then be replaced after about 1year. The implantation of a device for diagnostic purposes can only beexpected of a small number of very high-risk patients. The costs of animplantation are, of course, very high. Due to their design, implanteddevices are only of limited use as event recorders.

[0013] The technical solution as described in patent specification DE OS198 48 229 A1 describes an arrangement for recording and transmittingdigitalized medical data for monitoring a patient online, whichcomprises a data recording component (A) and a “mobile phone unit” (B)combined in a single device. ECG data is sent directly to the RAM memoryby the analog-to-digital converter and then from here directly to themobile phone unit. This means that it is not possible to treat and/orcontrol data, for example in the sense of data compression, as isevident from the two single figures in the specification, see directionsof the arrows for the signal path. The technical function must bequestioned in accordance with the contents of the disclosure of thespecification, as it is pointless to save the A/D converted signals 0.1without storing a quantity of data ordered and managed by a controllerproperly and system-compatibly in order to then process and/or use itfurther. Furthermore FIG. 1, as well as FIG. 2, of the patentspecification DE OS 198 48 229 does not allow the contents of the memoryto be read directly into a computer (PC). The characteristics named andclaimed in the principle claim of this patent specification DE OSsupport this evaluation, as the arrangement characteristics named hereare supposed to trigger the procedure characteristics “. . . todigitalize the analog recording data from the electrodes in theconverter, to store it in the electronic memory, and to transmit it fromhere from the mobile phone unit over a radio communications network . .. ”. In contrast to the facts presented above, a reading out of thememory is described in the specification section in Column 2, Lines 39to 41, which according to the contents of the disclosure of thisspecification, however, is not possible with this arrangement. A furtherdisadvantage of the technical solution described in patent specificationDE OS 198 48 229 is that only simple pulse rhythm irregularities can bedetected using the threshold switches specified here, and that it is notpossible to detect critical pulse irregularities, which in turn puts themedical value or the required safety of the patient in question.

[0014] Finally, it is also a disadvantage that the data acquisition andrecording unit, as well as the mobile phone unit, are combined in asingle device: it would surely be more practical and also moreeconomical to work with one data acquisition and recording unit and aconventional mobile telephone, rather than possibly having two of thelatter, due to the fact that the latter special, and otherwise unusable,mobile phone unit is already included in the technical solutiondescribed in patent specification DE OS 198 48 229.

[0015] Furthermore, all of this equipment together with the associatedprocedural processes is not able to record and store ECGs and totransmit them to an evaluation center for immediate processing,generally in computer systems, where necessary with the aid of anycommercially available, conventional radio telephone (mobile phone).

[0016] Taking into consideration the shortcomings of the state of theart described above and their causes, this invention is based on thepurpose of creating a method and an arrangement with which recorded ECGscan be transmitted automatically in any length, as well as triggering anautomatic transmission of ECG data in the event of critical pulseirregularities using a (commercially available) conventional mobiletelephone, and thereby forming an “ECG transmission” complex exploitingthe full potential of mobile telephones. A further purpose of theinvention should also be to realize such a high memory capacity so thatthe arrangement allows either discontinuous ECG monitoring over a longerperiod of days, weeks to months, or continuous ECG monitoring over 48hours, whereby removal of the storage medium should also be possible.Total mobility of the patient when recording ECGs and during datatransmission should also be ensured.

[0017] This purpose is fulfilled for a generic method and a genericarrangement according to the present invention by the features listed inthe characterizing part of the Claims 1 to 8.

[0018] An arrangement is hereby created which is represented by aportable recorder with the following principal modules: multi-channelamplifier, A/D converter, microcontroller, RAM and flash-ROM memoryelements, a removable flash card, pacemaker controller and interface. Amobile telephone unit was intentionally not included in the arrangementaccording to the invention, as this involves an associated unusableperformance in partially restricting special functionality. It was alsothe aim of the invention to implement according to the present inventionuniversal and commercially available mobile telephones (mobiles), ashave already been sold millions of times over, for data communication.Previously known, modem and recent technology for mobile patientmonitoring did not take this, economically, very important factor intoconsideration and always assumed that it would be able to integratemobile radio telephone technology into such a medical monitoring systemin a converted form for its own purposes. The advantages of separatingdata acquisition and recording from the mobile phone unit are obvious.In addition to simpler assembly and lower work, time, material and costexpenditure during manufacture, marketing and operation (particularlywith regard to the weight in the latter case), as otherwise deviceswould be “doubled”, any type of mobile phone (which is often availableanyway) can be used. This technical solution will, of course, always berepresented with a mobile telephone according to the present invention.The recorder modules allow data communication with the mobile telephonein such a way that a predefined telephone call is made when the mobilephone is so instructed by the recorder arrangement in order to be ableto use it to transmit ECG data with the patient's data using a suitabledata protocol, as well as a data and transmission backup. Only by meansof the arrangement or data processing of the, or by the, microcontrollerin the signal or data form differing to the nearest knowledge andtechnology (DE OS 198 48 229) according to the main characteristics ofthe invention, and by means of a special data protocol, is it possibleto carry out a multi-channel ECG transmission by means of datacompression of the individual channels, which also results in shortertransmission times. The aforementioned nearest knowledge and technologyis not aware of this resource-effect relationship. Here ECG data is sentfrom the A/D converter directly to the RAM memory and in turn from heredirectly to the mobile phone unit. As a result, a data-compressingtreatment/control of this data is not possible. Compared to thearrangement of the aforementioned nearest knowledge and technology, thisinvention produces advantageous effects of such proportions that in thecase of the solution in accordance with the invention as described heredata is compressed by the microcontroller before it is sent to themobile phone, which reduces the transmission time approximately by afactor of 5 compared to non-compressed transmission, and that accordingto this technical theory in accordance with the invention atheoretically unlimited number of individual ECG channels can betransmitted, even if the data quantities in the individual channelsdiffer from one another due to the various degrees of compression whichare possible. In contrast to the nearest knowledge and technology, thistechnical theory uses in accordance with the invention a memory cardemploying flash technology (flash card) for recording data. This methodof storage also allows data to be stored for 24 or 48 hours when used inconjunction with transmission by telephone, or it permits the storage ofa very large number of short-term individual events. It is thereforealso possible in a second mode to “Store Only” the short or long-termECG, thereby creating a new operating mode for the long-term ECG andevent recording methods. Furthermore the technical theory enables thepermanent storage of data using a flash card even when the battery ischanged or its power reserves are absolutely exhausted. This allowsrecorded data to be transmitted over a mobile phone at any time in thefuture, and no data loss occurs even when the battery is changed in themeantime. Finally, the flash card with the stored data employed inaccordance with the invention can be removed from the recorder and readinto a PC at another location. This expands the applicationpossibilities when storing large quantities of data. It is notabsolutely necessary to read out data via the serial interface.

[0019] The technical solution in accordance with the invention thereforehas the advantage of 3 methods, namely:

[0020] event recording in loop mode, including storage of the casehistory with the option of being able to transmit data immediately viamobile phone in case of emergency,

[0021] event storage for subsequent evaluation,

[0022] as well as

[0023] complete, continuous long-term ECG storage over a period ofseveral days.

[0024] To record an event it is only necessary to trigger recording bypressing one key; the following processes take place fullyautomatically.

[0025] Transmittance of ECG data in the event of critical pulseirregularities takes place automatically and safely by means of aspecial software. The threshold switches as specified in the currentknowledge and technology are only able to detect simple pulse rhythmirregularities, which puts the medical value or the required safety ofthe patient in question.

[0026] The invention is briefly described here in more detail using thesample model shown in FIG. 1.

[0027]FIG. 1 shows the block diagram, as can be used to illustrate theinvention. Three ECG signals are fed from the recorded analog signals 1to a three-channel amplifier 2 with its three channels 2.1, 2.2 and 2.3.The digitalized signals from the three channels 2.1, 2.2 and 2.3 are fedto the microprocessor 4, which for its part can influence the ANDconverter 3 if required and necessary. A data line to the pacemakercontroller 10 is also switched from one ECG channel, e.g. Channel 2.3,which detects the pacemaker impulse during a pacemaker ECG and marks theECG at the detected time and feeds it to the microcontroller 4.Processed data is stored according to its further purpose in the memoryarrangements 5 and 6 assigned in parallel to the microprocessor 4, fromwhere it is retrieved by the microcontroller 4 as required and can befurther or re-processed if necessary. The flash card 6 is designed to beremoved from the recorder arrangement, so that the data stored on thecard can be read into a PC at another location where it can then beprocessed and evaluated. This expands the application possibilities whenstoring large quantities of data. It is not absolutely necessary to readout data via the serial interface. The planned serial interface 7connected to the microcontroller 4 transfers the data either to a PC 9or the commercially available mobile telephone 8. Signal flow in theopposite direction from the mobile telephone 8 or the PC 9 to themicrocontroller 4 is also possible if required.

[0028] The recorder is configured with patient and transmission data viathe serial interface before the ECG monitor is put into operation.

[0029] At the evaluation center the patient is decoded and the ECG isassigned in the database. This ensures an absolutely fail-safeidentification. A received ECG is indicated so that an immediateevaluation is possible and the appropriate action can be initiated, e.g.the patient can be called using the mobile telephone or the emergencymedical service can be alarmed. If transmittance of the ECG cannot beassured due to inadequate radio transmission conditions, the call isrepeated. Should transmission still not take place, the stored ECG istransmitted together with the next event.

1. Method for recording and transmitting a multi-channel ECG as part ofa telemedical system (recorder—transmission element—evaluation center)in which the patient's medical data is permanently recorded,digitalized, stored and transmitted by radio signal to an evaluationcenter by means of a mobile arrangement worn on the body of the patient(recorder) for approximately simultaneous evaluation or monitoring.characterized in that following the recording of the ECG the signals (1)are prepared by means of a multi-channel amplifier (2) and a connectedA/D converter (3), that these signals are prepared accordingly and fedfrom (1) to a microcontroller (4) for processing, which if requiredqueries the A/D converter, that the data processed by themicrocontroller (4) is stored in a memory combination (5) andtime-related on a flash card (6), whereby here a flow-back of data fromthe memory elements (5) and (6) to the microcontroller is also allowedfor, that the microcontroller controls the serial interface (7) for therecorder configuration and the reading out of the processed ECG by meansof a special software in such a manner that, firstly, data can betransmitted to the mobile telephone (8) (Mobile Telephone mode) and,secondly, data can be read out directly to the computer (9) (PCCommunication mode), that one of the ECG signals emitted from themulti-channel amplifier (2) is fed to the pacemaker controller (10),which during a pacemaker ECG detects the pacemaker impulse, marks theECG at the detected time and feeds it to the microcontroller (4). 2.Method described in claim 1 , characterized in that followingtransmission/storage of the multi-channel ECG at an evaluation centerthe evaluation of this ECG can take place using known evaluationprograms.
 3. Method described in claim 1 , characterized in that apermanent monitoring of critical pulse irregularities, which require animmediate evaluation, takes place in the microcontroller (4) of therecorder arrangement by means of a special artifact-safe software andthat following detection of such an irregularity the current ECG, aswell as the ECG prior to this irregularity, are automaticallytransmitted in the Mobile Telephone mode to the evaluation center wherethe appropriate medical measures can be initiated.
 4. Method describedin claim 1 , characterized in that the telephone is automaticallyswitched on and the stored call number of the evaluation center isautomatically dialed with the aid of a special software in the MobileTelephone mode after an event has occurred.
 5. Method described inclaims 1 to 4 , characterized in that event recording and continuouslong-term monitoring can be carried out using the same method accordingto the aforementioned method characteristics and the same arrangement.6. Arrangement as a portable recorder for carrying out the procedureaccording to the aforementioned method characteristics, comprising anA/D converter unit, a memory unit, a microcontroller characterized inthat the ECG signals (1) are switched to a multi-channel amplifier (2)with the channels (2.1), (2.2), (2.3), . . . (2.X), whereby one or moreof the signals (1) can accumulate at a A/D converter (3) arranged afterthe amplifier (2), that the A/D converter (3) and a pacemaker controller(10), arranged in parallel to one another, are connected in series tothe amplifier (2), whereby these in turn are jointly applied to amicrocontroller (4), that the microcontroller (4) in its turn isinfluentially configured for the preceding A/D converter (2), that amemory combination (5) and a flash card (6), as well as a serialinterface, (7) are assigned to the microcontroller (4), alternatelyinfluential in both directions, whereby the serial interface providesaccess to the mobile telephone (8) and/or the computer (9). 7.Arrangement described in claim 6 , characterized in that the memorycombination (5) is composed of at least one RAM (5.1) and one flash ROM(5.2).
 8. Arrangement described in claim 6 , characterized in that theflash card (6) is not permanently installed in the recorder arrangement,but that it is designed to be removed.